Throttle override controlled by a vacuum boosted power brake system

ABSTRACT

A throttle override for a conventional throttle controlled internal combustion engine wherein an additional valve is positioned in the engine induction passage and is held closed by a spring but is normally held open during normal operation by a vacuum motor connected to the vacuum boosted power brake system of the vehicle.

Elnited States Patent [191 Ball et a1.

[451 Feb. 19, 1974 i 1 THROTTLE OVERRIDE CONTROLLED BY A VACUUM BOOSTEDPOWER BRAKE SYSTEM [75] Inventors: Frank W. Ball; Harold L. Howard,

both of Lansing, Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Dec. 8, 1972 [21] Appl. No.: 313,605

[52] U.S. Cl 192/3 M, 192/3 R [51] Int. Cl. F16d 67/00, Fl6d 71/00 [58]Field of Search 192/3 R, 3 T, 3 M, 3 TR;

[56] References Cited UNITED STATES PATENTS 3,495,692 2/1970 Holgate192/3 R 2,911,078 11/1959 Baker 192/3 R 2,311,120 2/1943 Mossinghoff....192/3 R 2,066,667 1/1937 Bellis 192/3 T X Primary Examiner-Benjamin W.Wyche Assistant Examiner-Lance W. Chandler Attorney, Agent, or FirmR. L.Phillips [5 7] ABSTRACT A throttle override for a conventional throttlecontrolled internal combustion engine wherein an additional valve ispositioned in the engine induction passage and is held closed by aspring but is normally held open during normal operation by a vacuummotor connected to the vacuum boosted power brake system of the vehicle.

2 Claims, 2 Drawing Figures F iwwim j THROTTLE OVERRIDE CONTROLLED BY AVACUUM BOOSTED POWER BRAKE SYSTEM SPECIFICATION The present inventionrelates to a throttle control for an internal combustion engine and moreparticularly to a throttle override mechanism for a vehicle to controlthe flow of air to the engine as a function of brake actuation.

During normal vehicle operation, it is customary to decelerate theengine before effecting vehicle braking, but under certain conditions,this is not always possible. There may therefore be times when thethrottle may not be returned to an idle or low idle position beforevehicle braking is required and, under these conditions, the engine willbe still operating to power the vehicle forward at the same time theoperator is attempting to brake the vehicle to a stop. This lattercondition will frequently occur, for example, with drivers who use theirleft foot for braking since their right foot may still be on theaccelerator pedal holding the throttle valve open as they attempt tobrake with their left foot.

It is therefore an object of this invention to provide a throttleoverride system for the internal combustion engine of a vehicle wherebya secondary valve is operable upon vehicle braking to control air flowto the engine in lieu of this air flow being controlled by the throttlevalve.

It is another object of this invention to provide an air flow controlsystem for the internal combustion engine ofa vehicle wherein, inaddition to the primary throttle valve for normally controlling the airflow in an engine air induction passage, a secondary air flow valvetherein is operatively connected with and closed by actuation of thevacuum boosted power brake system of the vehicle.

It is a further object to provide an engine speed control of theforegoing type wherein the secondary air flow valve is normally poweractuated by a vacuum motor to an open position but when the vacuumbooster unit of the vehicle vacuum boosted power brake system isoperated with at least a predetermined force the secondary air flowvalve is closed.

These and other objects of the invention are attained by means of an airflow control valve positioned in the air induction passage of the engineof a vehicle upstream of the throttle valve in an internally ventedcarburetor. The air flow valve is normally biased to a closed positionby a spring and is held open during normal engine operation by a vacuummotor connected to the vehicle vacuum system through the vacuum boosterunit of the vacuum boosted power brake system of the vehicle. The airflow valve is closed when the vacuum motor is placed in communicationwith the atmosphere upon actuation of the air valve of the vacuumbooster unit of the vehicle as the vehicle operator depresses thevehicle brake pedal to effect braking of the vehicle with at least apredetermined actuating force.

For a better understanding of the invention, as well as other objectsand further features thereof, reference is had to the following detaileddescription taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a view partially in schematic and partially in cross sectionwith parts broken away of a vehicle throttle override system provided inaccordance with the present invention; and

FIG. 2 is a sectional view of the air flow control valve and its poweractuator of the throttle override system of FIG. 1.

Referring now to FIG. 1, there is shown the internal combustion engineof a vehicle, not shown, the

operation of which is controlled by means of an accelerator pedal 11positioned for actuation by the vehicle operator. Accelerator pedal 11is connected by a suitable throttle linkage 12 to the throttle valve 13of a conventional carburetor 14 mounted on the engine 10 with the airpassage 15 therein in alignment with the induction passage 16 in theintake manifold 17 of the engine whereby the throttle valve 13 can bemoved between its open and closed positions to regulate the flow of airand fuel to the engine in a conventional manner, the return spring 18connected as shown normally returning throttle valve 13 to its idleposition upon removal of actuating force from pedal 11. Air is suppliedto the air passage 15 of the carburetor through the air intake duct 20of an air cleaner 21 mounted thereon. As shown, carburetor 14 isprovided with a fuel bowl 22 vented by vent passage 23 to the incomingair, the fuel bowl supplying fuel to the main fuel nozzle 24, idle port25 and off-idle port 26 of the carburetor in a conventional manner.

Referring now to the subject matter of the invention, the throttleoverride system includes an air flow control valve 27 positionedupstream of the throttle valve 13 whereby the air flow control valve canbe used to con trol the flow of air to the engine to limit engine speedindependent of the position of throttle valve 13. With this arrangement,the throttle valve 13 may be considered to be the primary valve normallycontrolling the operation of the engine while the air flow control valve27 can then be considered to be a secondary valve adapted to control theoperation of the engine in a manner and for a purpose to be described.

In the embodiment shown, a valve shaft 28 journaled in the air intake 20pivotally mounts the secondary valve 27 therein to be moved by adifferential fluid pressure operated motor, such as the vacuum motor 30,between an open position, as shown in the Figures, wherein air flow tothe engine is controlled in a normal manner by the throttle valve 13 anda closed position wherein the air flow to the engine is controlled bysecondary valve 27 regardless of the position of throttle valve 13. Thevariable pressure chamber of the vacuum motor 30 is selectively placedin communication either with the atmosphere or with the source of vacuumpressure, such as the vacuum in the induction passage 16 of the engine,as controlled by the air valve assembly in the vacuum booster unit 60 ofthe vehicle power brake system, generally designated 40, in a manner tobe described.

As best seen in FIG. 2, vacuum motor 30 comprises a housing formed bytwo generally cup-shaped parts, an upper part 31 and a lower part 32that securely seal'a diaphragm 33 therebetween to define a lower orvariable vacuum pressure chamber 34 and an upper or atmospheric chamber35, the vacuum chamber 34 being connected by a conduit 36 to communicatewith the variable pressure chamber of the vacuum booster unit 60 and theatmospheric chamber being open to the atmosphere through an aperture 37in the upper housing part 31. An actuator rod 38 is pivotally connectedat one end to the secondary valve 27 and at its other end to diaphragm33 to hold secondary valve27 in the open position, as shown, when asufficient differential pressure is created on the opposite sides ofdiaphragm 33. A spring 39 is positioned in the vacuum chamber 34abutting at one end against the lower housing part 32 and at its otherend against diaphragm 33 to normally bias diaphragm 33 in one direction,upward as shown in FIG. 2, to normally move secondary valve 27 to theclosed position when the pressure in the vacuum chamber 34 issufficiently increased so that the differential pressure on the oppositesides of diaphragm 33 is no longer sufficient to overcome the bias ofspring 39.

To permit engine idling when the secondary valve 27 is closed, clearancecan be provided between the secondary valve 27 and the interior wall ofthe air intake 20 to provide for a suitable air flow or, as shown, thevalve 27 can be provided with flow apertures 27a of the desired size forthe flow of sufficient air to the engine to maintain its operation at anidling speed.

Operation of the vacuum motor 30 is controlled by the operation of thevehicle braking system 40 whereby during normal vehicle operation, withthe vehicle braking system 40 in its released position, vacuum motor 30is vacuum actuated to hold secondary valve 27 in its open position sothat the operator has control of the engine operation in a conventionalmanner by the actuation of the throttle valve 13. However, when theoperator actuates the vehicle braking system 40 with at least apredetermined braking pressure, vacuum motor 30 is vented to allowspring 39 to effect movement of the secondary valve 27 to the closedposition to thus limit the air flow to the engine so that it can operateat a predetermined idling speed thus overriding the control of engineoperation by throttle valve 13.

As shown in FIG. 1, the vehicle braking system 40 is of the conventionaltype having a power brake unit of the combined vacuum and hydraulic unittype which uses engine intake manifold vacuum and atmospheric pressureto provide power assisted application of the vehicle brakes. This typeof power brake unit is composed of two main sections, a hydraulic mastercylinder assembly 50 and the vacuum power cylinder or booster unit 60.

The vacuum booster 60 may be either of the conventional double diaphragmtype or, as shown, a conventional single diaphragm type, such asdisclosed in the U. S. Pat. No. 3,249,021, issued May 3, 1966, toClarence R. Wuellner, and entitled Power Brake Booster. With referenceto FIG. 1, vacuum booster unit 60 has a push rod 41 pivotally connectedto the vehicle braking pedal 42 and has a piston rod 43 extending intothe hydraulic master cylinder assembly 50 which is connected by frontand rear brake lines 44 and 45, respectively, to the front and rearbrakes 46 and 47, respectively, to pump hydraulic pressure fluid theretowhereby braking ofthe set of vehicle wheels 48 is effected'.

Vacuum booster 60 comprises a housing formed by generally cup-shapedright and left housing parts 61 and 62, respectively, separated by acentrally apertured diaphragm 63 into the right chamber 64 and the leftchamber 65 with reference to FIG. 1. Right chamber 64 is selectivelyconnected, as to be hereinbelow described, to either left chamber 65 orto the atmosphere and is hereinafter called the variable pressurechamber 64. The left chamber 65 is connected by a conduit 66 with aone-way check valve 67 therein to communicate with the engine vacuumprovided at induction passage 16 and is hereinafter called the vacuumchamber 65. The outer periphery of diaphragm 63 is sealingly connectedbetween the right and left housing parts 61 and 62 and the innerperiphery of diaphragm 63 is sealingly connected to the radial flange 68of a tubular-shaped power piston 70 having a centrally located steppedbore 71 therethrough, one end of power piston 70 being of a reduceddiameter to be reciprocally received in a central aperture 72 of righthousing part 61. A dish-shapedsupport plate 69 is connected to the powerpiston flange 68 on the left side of diaphragm 63 for movementtherewith. The diaphragm 63, support plate 69 and power piston 70 form apower piston assembly that is movable as a unit within the vacuumbooster housing.

Power piston 70 is also provided with one or more radial passages 73extending through the tubular wall thereof and with one or more axialpassages 74, only one radial passage 73 being shown located 90 from itsactual position and only one axial passage 74 being shown. Each radialpassage 73 communicates with an axial slot 75 in stepped bore 71 and thevariable pressure chamber 64. Each axial passage 74 communicates at oneend with the portion of stepped bore 71 outboard of an annular shoulder76 located between the enlarged and reduced diameter portions of steppedbore 71 and at its other end with the vacuum chamber 65 through theenlarged left-hand bore end of power piston 70.

Reciprocably received in the reduced diameter por tion of stepped bore71 is an air valve seat member 77 that cooperates with an annularcentrally apertured floating air valve 78 to provide an air valve forselectively connecting variable pressure chamber 64 to communicate withthe atmosphere or with the vacuum chamber 65.

As described in greater detail in the hereinabove referenced US. Pat.No. 3,249,021 to Wuellner, floating air valve 78 is positionedconcentrically about push rod 41 and provides thereabout a centralpassage, the right end of which communicates with the atmosphere throughan annular filter 80 in the hub of the power piston and the left end ofwhich is normally seated against the right end of air valve seat member77. The right end of floating air valve 78 is sealingly retained in theenlarged diameter portion of stepped bore 71 and the left end offloating air valve 78 is biased leftwardly by a floating air valvespring 81 from a spring retainer 82 to normally seat on the right end ofair valve seat member 77, thereby normally blocking communicationbetween the variable pressure chamber 64 and the atmosphere.

An air valve spring 83 is positioned between the right end of thereaction assembly 84, which includes the piston rod 43, carried in theenlarged diameter portion of power piston 70 and a spring retainer cup85 suitably secured to the left end of air valve seat member 77 tonormally bias the air valve seat member 77, to the right as seen in P10.1, into seating relationship with the floating air valve 78. A powerpiston return spring 86 encircles the piston rod 43 within the vacuumchamber 65 to normally bias the power piston 70 to the right to theposition shown in FIG. 1 wherein the power piston 70 engages against thehousing part 61. This is the position of the aboveidentified elementswith the brake system 40 in its released position, that is, with nobraking pedal pressure being applied to brake pedal 42.

In the released position of the brake system 40, as shown in FIG. 1, theair valve seat member 77 is seated against floating air valve 78. Theflow of air under atmospheric pressure, which enters through the filter80 is blocked at the air valve seat member 77 which is seated againstthe floating air valve 78. In this position, the floating air valve 78is held away from the valve seat formed by annular shoulder'76 in thepower piston 70. Vacuum which is present at all times in vacuum chamber65 is free to evacuate the variable pressure chamber 64 with flowtherefrom being through radial passage 73, axial slot 75, the passagebetween shoulder 76 of the power piston and the floating air valve 78and then through the axial passage 74 in the power piston.

At the same time, vacuum in the variable pressure chamber 64 is appliedthrough conduit 36 to the vacuum chamber 34 of vacuum motor 30. Withvacuum pressure now present on one side of the diaphragm 33 of thismotor and atmospheric pressure on the other side, the vacuum motor 30 isvacuum actuated to hold actuator rod 38 in a retracted or downwardposition with reference to FIGS. 1 and 2 whereby secondary valve 27 isheld in its open position. Thus, whenever the brake system 40 isreturned to or is in a released position, secondary valve 27 will beheld in its open position.

When the vehicle operator applies the brakes by actuation of the brakepedal 42, the push rod 41 is moved to the left with reference to FIG. 1to carry with it the air valve seat member 77. With such leftwardmovement of air valve seat member 77, the floating air valve 78 isbiased leftwardly by floating air valve spring 81 to follow the airvalve seat member 77 until the floating air valve 78 seats on shoulder76 to block communication between the variable pressure chamber 64 andthe vacuum chamber 65 by closing off flow through axial passages 74.After the floating air valve 78 is stopped by shoulder 76 from followingleftward movement of air valve seat member 77, the air valve seat member77 is unseated from the floating air valve 78 to provide a passagetherebetween that connects the variable pressure chamber 64 tocommunicate with the atmosphere through radial passages 73, axial slots75, the central aperture in floating air valve 78, the enlarged diameterportion of stepped bore 71, and air filter 80. Since vacuum chamber 65is connected to communicate with engine vacuum provided in inductionpassage 16 of engine 10, this allows a leftwardly acting pressuredifferential to be created on the opposite sides of diaphragm 63 withthe pressure in the variable pressure chamber 64 approaching atmosphericpressure upon the application of a predetermined force applied to brakepedal 42. This pressure differential causes diaphragm 63, power piston70 and support plate 69 to move to the left from the position shown inFIG. 1, thereby effecting a corresponding leftward movement of reactionassembly 84 and its piston rod 43 to effect vehicle braking.

When a desired pedal pressure is reached, the power piston 70 has movedto the left sufficiently until the floating air valve 78, which is stillseated against shoulder 76, again seats on the air valve seat member 77.Seating of the floating air valve on the air valve seat member shuts offthe flow of air at atmospheric pressure and seals the reduced vacuumlevel in the variable pressure chamber which provides the power assistas this pressure acts against the diaphragm and power piston. Theelements of the power brake unit are now in the holding position andwill then remain in this rela tionship to each other until eitherpressure is applied or released at the brake pedal 42.

As the pressure in variable pressure chamber 64 increases to atmosphericpressure, which will occur when the brake pedal is actuated with atleast a predetermined force, this air under pressure will flow from thischamber through conduit 36 to vacuum chamber 34 of vacuum motor 30thereby allowing spring 39 to effect movement of secondary valve 27 toits closed position in the manner hereinabove described. As long as thebrake pedal pressure, above a predetermined value, is applied, spring 39will hold the secondary valve 27 in the closed position. With valve 27held in the closed position, air flow to the engine 10 is restricted,irrespective of the position of throttle valve 13, to a predeterminedflow rate so that the operation of the engine will be reduced to an idlespeed mode of operation with adequate fuel flowing from the idle port 25and off-idle port 26 of the carburetor to maintain engine operation atthis reduced operating speed. If throttle valve 13 is open whensecondary air flow valve 27 is closed upon application of thepredetermined braking force, carburetor l4 continues to operate as aconventional internally vented carburetor in providing an air-fuel flowsufficient to idle engine 10 with fuel being supplied from the idle andoff-idle ports of the carburetor.

Upon removal of actuating force from vehicle brake pedal 42, powerpiston 70 and air valve seat member 77 are returned rightwardly to theirnon-actuated or released positions, as previously described, by thepower piston return spring 86 and air valve spring 83, therebyre-establishing the normal communication between the variable pressurechamber 64 and the vacuum chamber while blocking communication betweenthe variable pressure chamber 64 and the atmosphere so that vacuum isagain applied in variable pressure chamber 64. As this occurs, vacuum isagain applied to the vacuum chamber 34 of vacuum motor 30 so that vacuummotor 30 will effect movement of the valve 27 back to its normally openposition with engine operation then controlled by throttle valve 13.

Engine 10 is thus operated at an idling speed whenever a braking forceabove a predetermined amount is applied to the vehicle braking system,and such idle speed operation is effected whether the vehicle operatorinadvertently holds the throttle valve 13 open or not. Thus, the enginewould be similarly operated at the idling condition even if the throttlelinkage 12 or return spring 18 should for some reason not effect anormal return of throttle valve 13 to its idle position on removal ofactuating force from throttle pedal 11.

Having described one embodiment of the present invention, it isunderstood that the specific terms and examples are employed in adescriptive sense only and not for the purposes of limitation. Otherembodiments of the invention, modifications thereof, and alternativesthereto may be used. We therefore aim in the appended claims to coversuch modifications and changes as are within the true spirit and scopeof our invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. In a vehicle including an internal combustion engine providing asource of engine vacuum and having an air induction passage, an operatorcontrolled primary throttle valve pivotably mounted in the air inductionpassage to normally regulate an air-fuel flow to the engine; and avacuum boosted power braking system including a brake pedal, hydraulicpump means bydraulically connected to the set of vehicle wheel brakes,and a vacuum booster unit operatively connected to the hydraulic pumpmeans, the vacuum booster unit having a first pressure chamber, a secondpressure chamber, and air valve means actuatable by actuation of thebrake pedal, the first pressure chamber being connected to the source ofengine vacuum and the second pressure chamber being selectivelyconnectable by the air valve means to the first pressure chamber whenthe brake pedal is not actuated and to the atmosphere when the brakepedal is actuated:

a. secondary valve means pivotably mounted in the air induction passageupstream of the primary throttle valve for movement between an openposition and a closed position;

b. differential fluid pressure actuated power means connected to saidsecondary valve means to effect movement thereof between said closedposition and said open position, said differential fluid pressureactuated power means includes a housing, a diaphragm, and a spring, saiddiaphragm separating said housing into a first chamber and a secondchamber, said diaphragm being operatively connected to said secondaryvalve to effect movement thereof between said open position and saidclosed position, said spring being positioned in said first chamber inabutment against said diaphragm to normally bias said diaphragm to movesaid air valve to said closed position,

c. conduit means connecting the second pressure chamber of the vacuumbooster unit to communicate with said first chamber of said differentialfluid pressure actuated power means to effect movement of said secondaryvalve to said open position when the brake pedal is not actuated and toconnect said first chamber to the atmosphere when the brake pedal isactuated with a predetermined actuating force,

2. in a vehicle having an internal combustion engine providing a sourceof engine vacuum; a carburetor hav ing an air induction passage, anoperator controlled throttle valve for normally regulating the air fuelflow to the engine; an air cleaner having an air intake passage mountedon the carburetor for delivering clean air to the air induction passage;and a vacuum boosted power braking system including a brake pedal,hydraulic pump means hydraulically connected to the set of vehicle wheelbrakes, and a vacuum booster unit having a first pressure chamber, asecond pressure chamber, an air valve means actuatable upon actuation ofthe brake pedal, said first pressure chamber being connected to a sourceof engine vacuum and the second pressure chamber being selectivelyconnected by the air valve means to communicate with the first chamberwhen the brake pedal is not actuated and with the atmosphere when thebrake pedal is actuated;

a. a secondary valve mounted in the air intake passage of the aircleaner for movement between an open position allowing a normal airdelivery to the engine and an air flow reducing position for restrictingthe air flow to the engine;

b. differential fluid pressure actuated power means including a housingand a diaphragm, said diaphragm separating said housing into a firstchamber and a second chamber, said first chamber being operativelyconnected to communicate with the second chamber of the vacuum boosterunit and said second chamber being connected to communicate with theatmosphere, said diaphragm being operatively connected to said secondaryvalve to effect movement thereof from said air flow reducing position tosaid open position; and

c. spring means operatively connected to said secondary valve to effectmovement thereof from said open position to said closed position whenthe vehicle brake pedal is actuated with more than a predeterminedbraking effort.

1. In a vehicle including an internal combustion engine providing asource of engine vacuum and having an air induction passage, an operatorcontrolled primary throttle valve pivotably mounted in the air inductionpassage to normally regulate an airfuel flow to the engine; and a vacuumboosted power braking system including a brake pedal, hydraulic pumpmeans hydraulically connected to the set of vehicle wheel brakes, and avacuum booster unit operatively connected to the hydraulic pump means,the vacuum booster unit having a first pressure chamber, a secondpressure chamber, and air valve means actuatable by actuation of thebrake pedal, the first pressure chamber being connected to the source ofengine vacuum and the second pressure chamber being selectivelyconnectable by the air valve means to the first pressure chamber whenthe brake pedal is not actuated and to the atmosphere when the brakepedal is actuated: a. secondary valve means pivotably mounted in the airinduction passage upstream of the primary throttle valve for movementbetween an open position and a closed position; b. differential fluidpressure actuated power means connected to said secondary valve means toeffect movement thereof between said closed position and said openposition, said differential fluid pressure actuated power means includesa housing, a diaphragm, and a spring, said diaphragm separating saidhousing into a first chamber and a second chamber, said diaphragm beingoperatively connected to said secondary valve to effect movement thereofbetween said open position and said closed position, said spring beingpositioned in said first chamber in abutment against said diaphragm tonormally bias said diaphragm to move said air valve to said closedposition, c. conduit means connecting the second pressure chamber of thevacuum booster unit to communicate with said first chamber of saiddifferential fluid pressure actuated power means to effect movement ofsaid secondary valve to said open position when the brake pedal is notactuated and to connect said first chamber to the atmosphere when thebrake pedal is actuated with a predetermined actuating force.
 2. In avehicle having an internal combustion engine providing a source ofengine vacuum; a carburetor having an air induction passage, an operatorcontrolled throttle valve for normally regulating the air fuel flow tothe engine; an air cleaner having an air intake passage mounted on thecarburetor for delivering clean air to the air induction passage; and avacuum boosted poweR braking system including a brake pedal, hydraulicpump means hydraulically connected to the set of vehicle wheel brakes,and a vacuum booster unit having a first pressure chamber, a secondpressure chamber, an air valve means actuatable upon actuation of thebrake pedal, said first pressure chamber being connected to a source ofengine vacuum and the second pressure chamber being selectivelyconnected by the air valve means to communicate with the first chamberwhen the brake pedal is not actuated and with the atmosphere when thebrake pedal is actuated; a. a secondary valve mounted in the air intakepassage of the air cleaner for movement between an open positionallowing a normal air delivery to the engine and an air flow reducingposition for restricting the air flow to the engine; b. differentialfluid pressure actuated power means including a housing and a diaphragm,said diaphragm separating said housing into a first chamber and a secondchamber, said first chamber being operatively connected to communicatewith the second chamber of the vacuum booster unit and said secondchamber being connected to communicate with the atmosphere, saiddiaphragm being operatively connected to said secondary valve to effectmovement thereof from said air flow reducing position to said openposition; and c. spring means operatively connected to said secondaryvalve to effect movement thereof from said open position to said closedposition when the vehicle brake pedal is actuated with more than apredetermined braking effort.